In this study, we observed that TGGG hybrid grouper exhibited negative allometric growth (b < 3) in the beginning of the experiment (day 0) at all temperature and diets, whereas the opposite was observed in FM (day 30). Isometric growth was observed at 26°C when fish were fed on both diets and at 30°C when fish were fed on pellet. Positive allometric growth was observed at 30°C when fish were fed on shrimp. Negative allometric growth was observed at 34°C and 22°C when fish were fed on both diets (Table 1). The LWRs of TGGG hybrid grouper raised in similar temperatures and diets have not been previously recorded in Malaysia or elsewhere, thereby preventing a direct comparison with earlier results. The only report on LWR of TGGG hybrid grouper in Malaysia was at different temperatures in the range 28°C-29.5°C and negative allometric growth was documented (Luin et al. 2013), which is in agreement with all temperature ranges at the beginning of the experiment (day 0) and 22°C and 34°C in FM (30 d). This result indicated that fish becomes lighter as it increased in size. Moreover, the calculated isometric growth (b = 3) at 26°C when fish were fed on pellet and shrimp and that at 30°C when fish were fed on pellet diet in FM are in harmony with their parental species namely, giant grouper (E. lanceolatus) b = 3 (IGFA 2001) and tiger grouper (E. fuscoguttatus) b = 3 (Agembe et al. 2010; Kulbicki et al. 2005; Palomares & Pagdilao 1988) in other geographic locations (Table 2). At 22°C and 34°C, fish represented negative allometric growth in both IM and FM when fed on shrimp and pellet diets, as observed with other Epinephelus sp. (Table 2). This variation in allometric coefficient for TGGG hybrid grouper in this study might be attributed to differences in locations, feeding conditions, temperatures, sample sizes and stages of maturity (Salam & Davies 1994). Nevertheless, the allometric coefficients (b) estimated in this study were within the expected range of 2-4, as commonly observed in teleosts (Bagenal & Tesch 1978) except at 22°C FM with pellet diet (b = 1.87). TGGG hybrid grouper generally showed negative allometric growth. However, at 26°C and 30°C with pellet or shrimp diet, the grouper can exhibit isometric (26oC fed on both diet and 30oC on pellet diet only) and positive allometric growth patterns (30oC fed shrimp diet only). Thus, at 26°C and 30°C, progression in growth of the body weight vis-a-vis body length was as expected of a healthy and robust fish. The samples were collected from a local land-based hatchery where the temperature was maintained at 26°C. However, in most cases, the TGGG hybrid grouper that were reared in marine and brackish water cages and were exposed to higher temperature ranges could demonstrate a positive allometric growth. In addition, a higher temperature could increase the metabolic rates of fish (Temming & Herrmann 2001), thereby accelerating
their digestion process (De et al. 2014) and inducing better (isometric and positive allometric) growth. The hybrid grouper was grown under better conditions at 26°C and 30°C than at 22°C and 34°C (Table 1). Increasing K and Kn values were observed in IM and FM at 26°C and 30°C (i.e. better condition), whereas decreasing K and Kn values were observed at 34°C and 22°C (i.e. poor condition) regardless of diet (Figure 2). At 22°C, visceral fat was crucial for the survival of seldomfed fish (Braga 1986). Braga (1986) and Oni et al. (1983) showed that the values of the condition factor could vary across different seasons and could be influenced by biotic and abiotic factors. The radical change in temperature from 26°C to 22°C and to 34°C could be attributed to such differences in conditions. The K and Kn values did not significantly vary in IM, which could be attributed to the short dwelling time in different temperature for the shrimp- and pellet-fed fish (Helmuth et al. 2010). To the best of our knowledge, no previous study has investigated the condition of grouper fish, thereby preventing a direct comparison of our findings with previous results.